Synthesis of VB2-V3B4-V2B3/VC hybrid powders via powder metallurgy processes

Abstract

The present study reports the in-situ synthesis of hybrid powders containing vanadium borides (VB 2 , V 3 B 4 and V 2 B 3 ) and vanadium carbide (VC) using powder metallurgy methods. VB 2 -V 3 B 4 -V 2 B 3 /VC hybrid powders were synthesized from V 2 O 5 , B 2 O 3 and C powder blends via a carbothermal reduction route assisted by mechanical milling. Powder blends were mechanically milled up to 5 h in a high-energy ball mill. The milling process reduced the crystallite size, increased the uniformity of the particle distribution and hence increased the reactivity of the starting powders. As-blended and milled powders were annealed at different temperatures (1400, 1500 and 1600°C) for 12 h to investigate the probability of achieving vanadium boride and carbide phases simultaneously. Annealed powders were characterized using X-ray diffractometer (XRD), scanning electron microscope/energy dispersive spectrometer (SEM/EDS) and particle size analyzer. In case of using annealing temperature of 1400°C, VB 2 -V 3 B 4 -V 2 B 3 /VC hybrid powders were obtained with an amount of unreacted V 2 O 5 . Annealing temperatures of 1500 and 1600 ° C resulted in the formation of VB 2 , V 3 B 4 , V 2 B 3 and VC phases. Milling affected the weight percentages of the phases as well as the type of major boride phase.